lldb/source/Plugins/Process/Linux/NativeThreadLinux.cpp

//===-- NativeThreadLinux.cpp --------------------------------- -*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "NativeThreadLinux.h"

#include <signal.h>
#include <sstream>

#include "NativeProcessLinux.h"
#include "NativeRegisterContextLinux.h"
#include "SingleStepCheck.h"

#include "lldb/Core/Log.h"
#include "lldb/Core/State.h"
#include "lldb/Host/HostNativeThread.h"
#include "lldb/Host/linux/Ptrace.h"
#include "lldb/Utility/LLDBAssert.h"
#include "lldb/lldb-enumerations.h"

#include "llvm/ADT/SmallString.h"

#include "Plugins/Process/POSIX/CrashReason.h"

#include <sys/syscall.h>
// Try to define a macro to encapsulate the tgkill syscall
#define tgkill(pid, tid, sig) \
    syscall(SYS_tgkill, static_cast< ::pid_t>(pid), static_cast< ::pid_t>(tid), sig)

using namespace lldb;
using namespace lldb_private;
using namespace lldb_private::process_linux;

namespace
{
    void LogThreadStopInfo (Log &log, const ThreadStopInfo &stop_info, const char *const header)
    {
        switch (stop_info.reason)
        {
            case eStopReasonNone:
                log.Printf ("%s: %s no stop reason", __FUNCTION__, header);
                return;
            case eStopReasonTrace:
                log.Printf ("%s: %s trace, stopping signal 0x%" PRIx32, __FUNCTION__, header, stop_info.details.signal.signo);
                return;
            case eStopReasonBreakpoint:
                log.Printf ("%s: %s breakpoint, stopping signal 0x%" PRIx32, __FUNCTION__, header, stop_info.details.signal.signo);
                return;
            case eStopReasonWatchpoint:
                log.Printf ("%s: %s watchpoint, stopping signal 0x%" PRIx32, __FUNCTION__, header, stop_info.details.signal.signo);
                return;
            case eStopReasonSignal:
                log.Printf ("%s: %s signal 0x%02" PRIx32, __FUNCTION__, header, stop_info.details.signal.signo);
                return;
            case eStopReasonException:
                log.Printf ("%s: %s exception type 0x%02" PRIx64, __FUNCTION__, header, stop_info.details.exception.type);
                return;
            case eStopReasonExec:
                log.Printf ("%s: %s exec, stopping signal 0x%" PRIx32, __FUNCTION__, header, stop_info.details.signal.signo);
                return;
            case eStopReasonPlanComplete:
                log.Printf ("%s: %s plan complete", __FUNCTION__, header);
                return;
            case eStopReasonThreadExiting:
                log.Printf ("%s: %s thread exiting", __FUNCTION__, header);
                return;
            case eStopReasonInstrumentation:
                log.Printf ("%s: %s instrumentation", __FUNCTION__, header);
                return;
            default:
                log.Printf ("%s: %s invalid stop reason %" PRIu32, __FUNCTION__, header, static_cast<uint32_t> (stop_info.reason));
        }
    }
}

NativeThreadLinux::NativeThreadLinux (NativeProcessLinux *process, lldb::tid_t tid) :
    NativeThreadProtocol (process, tid),
    m_state (StateType::eStateInvalid),
    m_stop_info (),
    m_reg_context_sp (),
    m_stop_description ()
{
}

std::string
NativeThreadLinux::GetName()
{
    NativeProcessProtocolSP process_sp = m_process_wp.lock ();
    if (!process_sp)
        return "<unknown: no process>";

    // const NativeProcessLinux *const process = reinterpret_cast<NativeProcessLinux*> (process_sp->get ());
    llvm::SmallString<32> thread_name;
    HostNativeThread::GetName(GetID(), thread_name);
    return thread_name.c_str();
}

lldb::StateType
NativeThreadLinux::GetState ()
{
    return m_state;
}


bool
NativeThreadLinux::GetStopReason (ThreadStopInfo &stop_info, std::string& description)
{
    Log *log (GetLogIfAllCategoriesSet (LIBLLDB_LOG_THREAD));

    description.clear();

    switch (m_state)
    {
    case eStateStopped:
    case eStateCrashed:
    case eStateExited:
    case eStateSuspended:
    case eStateUnloaded:
        if (log)
            LogThreadStopInfo (*log, m_stop_info, "m_stop_info in thread:");
        stop_info = m_stop_info;
        description = m_stop_description;
        if (log)
            LogThreadStopInfo (*log, stop_info, "returned stop_info:");

        return true;

    case eStateInvalid:
    case eStateConnected:
    case eStateAttaching:
    case eStateLaunching:
    case eStateRunning:
    case eStateStepping:
    case eStateDetached:
        if (log)
        {
            log->Printf ("NativeThreadLinux::%s tid %" PRIu64 " in state %s cannot answer stop reason",
                    __FUNCTION__, GetID (), StateAsCString (m_state));
        }
        return false;
    }
    llvm_unreachable("unhandled StateType!");
}

NativeRegisterContextSP
NativeThreadLinux::GetRegisterContext ()
{
    // Return the register context if we already created it.
    if (m_reg_context_sp)
        return m_reg_context_sp;

    NativeProcessProtocolSP m_process_sp = m_process_wp.lock ();
    if (!m_process_sp)
        return NativeRegisterContextSP ();

    ArchSpec target_arch;
    if (!m_process_sp->GetArchitecture (target_arch))
        return NativeRegisterContextSP ();

    const uint32_t concrete_frame_idx = 0;
    m_reg_context_sp.reset (NativeRegisterContextLinux::CreateHostNativeRegisterContextLinux(target_arch,
                                                                                             *this,
                                                                                             concrete_frame_idx));

    return m_reg_context_sp;
}

Error
NativeThreadLinux::SetWatchpoint (lldb::addr_t addr, size_t size, uint32_t watch_flags, bool hardware)
{
    if (!hardware)
        return Error ("not implemented");
    if (m_state == eStateLaunching)
        return Error ();
    Error error = RemoveWatchpoint(addr);
    if (error.Fail()) return error;
    NativeRegisterContextSP reg_ctx = GetRegisterContext ();
    uint32_t wp_index =
        reg_ctx->SetHardwareWatchpoint (addr, size, watch_flags);
    if (wp_index == LLDB_INVALID_INDEX32)
        return Error ("Setting hardware watchpoint failed.");
    m_watchpoint_index_map.insert({addr, wp_index});
    return Error ();
}

Error
NativeThreadLinux::RemoveWatchpoint (lldb::addr_t addr)
{
    auto wp = m_watchpoint_index_map.find(addr);
    if (wp == m_watchpoint_index_map.end())
        return Error ();
    uint32_t wp_index = wp->second;
    m_watchpoint_index_map.erase(wp);
    if (GetRegisterContext()->ClearHardwareWatchpoint(wp_index))
        return Error ();
    return Error ("Clearing hardware watchpoint failed.");
}

Error
NativeThreadLinux::Resume(uint32_t signo)
{
    const StateType new_state = StateType::eStateRunning;
    MaybeLogStateChange (new_state);
    m_state = new_state;

    m_stop_info.reason = StopReason::eStopReasonNone;
    m_stop_description.clear();

    // If watchpoints have been set, but none on this thread,
    // then this is a new thread. So set all existing watchpoints.
    if (m_watchpoint_index_map.empty())
    {
        NativeProcessLinux &process = GetProcess();

        const auto &watchpoint_map = process.GetWatchpointMap();
        GetRegisterContext()->ClearAllHardwareWatchpoints();
        for (const auto &pair : watchpoint_map)
        {
            const auto &wp = pair.second;
            SetWatchpoint(wp.m_addr, wp.m_size, wp.m_watch_flags, wp.m_hardware);
        }
    }

    intptr_t data = 0;

    if (signo != LLDB_INVALID_SIGNAL_NUMBER)
        data = signo;

    return NativeProcessLinux::PtraceWrapper(PTRACE_CONT, GetID(), nullptr, reinterpret_cast<void *>(data));
}

void
NativeThreadLinux::MaybePrepareSingleStepWorkaround()
{
    if (!SingleStepWorkaroundNeeded())
        return;

    Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_THREAD));

    if (sched_getaffinity(static_cast<::pid_t>(m_tid), sizeof m_original_cpu_set, &m_original_cpu_set) != 0)
    {
        // This should really not fail. But, just in case...
        if (log)
        {
            Error error(errno, eErrorTypePOSIX);
            log->Printf("NativeThreadLinux::%s Unable to get cpu affinity for thread %" PRIx64 ": %s", __FUNCTION__,
                        m_tid, error.AsCString());
        }
        return;
    }

    cpu_set_t set;
    CPU_ZERO(&set);
    CPU_SET(0, &set);
    if (sched_setaffinity(static_cast<::pid_t>(m_tid), sizeof set, &set) != 0 && log)
    {
        // This may fail in very locked down systems, if the thread is not allowed to run on
        // cpu 0. If that happens, only thing we can do is it log it and continue...
        Error error(errno, eErrorTypePOSIX);
        log->Printf("NativeThreadLinux::%s Unable to set cpu affinity for thread %" PRIx64 ": %s", __FUNCTION__, m_tid,
                    error.AsCString());
    }
}

void
NativeThreadLinux::MaybeCleanupSingleStepWorkaround()
{
    if (!SingleStepWorkaroundNeeded())
        return;

    if (sched_setaffinity(static_cast<::pid_t>(m_tid), sizeof m_original_cpu_set, &m_original_cpu_set) != 0)
    {
        Error error(errno, eErrorTypePOSIX);
        Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_THREAD));
        log->Printf("NativeThreadLinux::%s Unable to reset cpu affinity for thread %" PRIx64 ": %s", __FUNCTION__,
                    m_tid, error.AsCString());
    }
}

Error
NativeThreadLinux::SingleStep(uint32_t signo)
{
    const StateType new_state = StateType::eStateStepping;
    MaybeLogStateChange (new_state);
    m_state = new_state;
    m_stop_info.reason = StopReason::eStopReasonNone;

    MaybePrepareSingleStepWorkaround();

    intptr_t data = 0;
    if (signo != LLDB_INVALID_SIGNAL_NUMBER)
        data = signo;

    // If hardware single-stepping is not supported, we just do a continue. The breakpoint on the
    // next instruction has been setup in NativeProcessLinux::Resume.
    return NativeProcessLinux::PtraceWrapper(GetProcess().SupportHardwareSingleStepping() ? PTRACE_SINGLESTEP
                                                                                          : PTRACE_CONT,
                                             m_tid, nullptr, reinterpret_cast<void *>(data));
}

void
NativeThreadLinux::SetStoppedBySignal(uint32_t signo, const siginfo_t *info)
{
    Log *log (GetLogIfAllCategoriesSet (LIBLLDB_LOG_THREAD));
    if (log)
        log->Printf ("NativeThreadLinux::%s called with signal 0x%02" PRIx32, __FUNCTION__, signo);

    SetStopped();

    m_stop_info.reason = StopReason::eStopReasonSignal;
    m_stop_info.details.signal.signo = signo;

    m_stop_description.clear();
    if (info)
    {
        switch (signo)
        {
        case SIGSEGV:
        case SIGBUS:
        case SIGFPE:
        case SIGILL:
             //In case of MIPS64 target, SI_KERNEL is generated for invalid 64bit address.
             const auto reason = (info->si_signo == SIGBUS && info->si_code == SI_KERNEL) ? 
                                  CrashReason::eInvalidAddress : GetCrashReason(*info);
             m_stop_description = GetCrashReasonString(reason, reinterpret_cast<uintptr_t>(info->si_addr));
             break;
        }
    }
}

bool
NativeThreadLinux::IsStopped (int *signo)
{
    if (!StateIsStoppedState (m_state, false))
        return false;

    // If we are stopped by a signal, return the signo.
    if (signo &&
        m_state == StateType::eStateStopped &&
        m_stop_info.reason == StopReason::eStopReasonSignal)
    {
        *signo = m_stop_info.details.signal.signo;
    }

    // Regardless, we are stopped.
    return true;
}

void
NativeThreadLinux::SetStopped()
{
    if (m_state == StateType::eStateStepping)
        MaybeCleanupSingleStepWorkaround();

    const StateType new_state = StateType::eStateStopped;
    MaybeLogStateChange(new_state);
    m_state = new_state;
    m_stop_description.clear();
}

void
NativeThreadLinux::SetStoppedByExec ()
{
    Log *log (GetLogIfAllCategoriesSet (LIBLLDB_LOG_THREAD));
    if (log)
        log->Printf ("NativeThreadLinux::%s()", __FUNCTION__);

    SetStopped();

    m_stop_info.reason = StopReason::eStopReasonExec;
    m_stop_info.details.signal.signo = SIGSTOP;
}

void
NativeThreadLinux::SetStoppedByBreakpoint ()
{
    SetStopped();

    m_stop_info.reason = StopReason::eStopReasonBreakpoint;
    m_stop_info.details.signal.signo = SIGTRAP;
    m_stop_description.clear();
}

void
NativeThreadLinux::SetStoppedByWatchpoint (uint32_t wp_index)
{
    SetStopped();

    lldbassert(wp_index != LLDB_INVALID_INDEX32 &&
               "wp_index cannot be invalid");

    std::ostringstream ostr;
    ostr << GetRegisterContext()->GetWatchpointAddress(wp_index) << " ";
    ostr << wp_index;

    /*
     * MIPS: Last 3bits of the watchpoint address are masked by the kernel. For example:
     * 'n' is at 0x120010d00 and 'm' is 0x120010d04. When a watchpoint is set at 'm', then
     * watch exception is generated even when 'n' is read/written. To handle this case,
     * find the base address of the load/store instruction and append it in the stop-info 
     * packet.
    */
    ostr << " " << GetRegisterContext()->GetWatchpointHitAddress(wp_index);

    m_stop_description = ostr.str();

    m_stop_info.reason = StopReason::eStopReasonWatchpoint;
    m_stop_info.details.signal.signo = SIGTRAP;
}

bool
NativeThreadLinux::IsStoppedAtBreakpoint ()
{
    return GetState () == StateType::eStateStopped &&
        m_stop_info.reason == StopReason::eStopReasonBreakpoint;
}

bool
NativeThreadLinux::IsStoppedAtWatchpoint ()
{
    return GetState () == StateType::eStateStopped &&
        m_stop_info.reason == StopReason::eStopReasonWatchpoint;
}

void
NativeThreadLinux::SetStoppedByTrace ()
{
    SetStopped();

    m_stop_info.reason = StopReason::eStopReasonTrace;
    m_stop_info.details.signal.signo = SIGTRAP;
}

void
NativeThreadLinux::SetStoppedWithNoReason ()
{
    SetStopped();

    m_stop_info.reason = StopReason::eStopReasonNone;
    m_stop_info.details.signal.signo = 0;
}

void
NativeThreadLinux::SetExited ()
{
    const StateType new_state = StateType::eStateExited;
    MaybeLogStateChange (new_state);
    m_state = new_state;

    m_stop_info.reason = StopReason::eStopReasonThreadExiting;
}

Error
NativeThreadLinux::RequestStop ()
{
    Log* log (GetLogIfAllCategoriesSet (LIBLLDB_LOG_THREAD));

    NativeProcessLinux &process = GetProcess();

    lldb::pid_t pid = process.GetID();
    lldb::tid_t tid = GetID();

    if (log)
        log->Printf ("NativeThreadLinux::%s requesting thread stop(pid: %" PRIu64 ", tid: %" PRIu64 ")", __FUNCTION__, pid, tid);

    Error err;
    errno = 0;
    if (::tgkill (pid, tid, SIGSTOP) != 0)
    {
        err.SetErrorToErrno ();
        if (log)
            log->Printf ("NativeThreadLinux::%s tgkill(%" PRIu64 ", %" PRIu64 ", SIGSTOP) failed: %s", __FUNCTION__, pid, tid, err.AsCString ());
    }

    return err;
}

void
NativeThreadLinux::MaybeLogStateChange (lldb::StateType new_state)
{
    Log *log (GetLogIfAllCategoriesSet (LIBLLDB_LOG_THREAD));
    // If we're not logging, we're done.
    if (!log)
        return;

    // If this is a state change to the same state, we're done.
    lldb::StateType old_state = m_state;
    if (new_state == old_state)
        return;

    NativeProcessProtocolSP m_process_sp = m_process_wp.lock ();
    lldb::pid_t pid = m_process_sp ? m_process_sp->GetID () : LLDB_INVALID_PROCESS_ID;

    // Log it.
    log->Printf ("NativeThreadLinux: thread (pid=%" PRIu64 ", tid=%" PRIu64 ") changing from state %s to %s", pid, GetID (), StateAsCString (old_state), StateAsCString (new_state));
}

NativeProcessLinux &
NativeThreadLinux::GetProcess()
{
    auto process_sp = std::static_pointer_cast<NativeProcessLinux>(NativeThreadProtocol::GetProcess());
    assert(process_sp);
    return *process_sp;
}